package com.crayon2f.test;

import com.crayon2f.test.beans.User;
import org.junit.Test;

import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;

/**
 * Created by feifan.gou@gmail.com on 2021/2/5 17:00.
 */
public class TreeMapSource {

    @Test
    public void test() {

        Map<String, String> treeMap = new TreeMap<>();
        treeMap.put(null, "1");
//        treeMap.put(null, "1");
        System.out.println(treeMap);
    }
}
